<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    var canVisitAllRooms = function (rooms) {
      let pass = rooms[0],
        index = 1
      rooms[0] = false
      while (pass.length > 0) {
        let arr = pass.splice(0, pass.length)
        for (let item of arr) {
          if (rooms[item] !== false) {
            pass.push(...rooms[item].splice(0, rooms[item].length))
            index++
            rooms[item] = false
          }
        }
      }
      return index == rooms.length
    }
    console.log(canVisitAllRooms([[1], [2], [3], []]));
  </script>
</body>

</html>